Gitzo GT2541 or GT3541 ? Dilemma

I own already a Gitzo tripod (GT 1258) bought in 2006 which seems to me a bit limited about the weight it can support (as per the spec) at 8 kg

I using D3s plus 24-70 F2.8 (scenic view/panorama/HDR), 70-200 F2.8 and 300 F2.8 sometime with TC2.0 or TC1.7 (wildlife)

My dilemma is about selecting a GT2541 (12kg) or a GT3541 (18kg); 4 leg sections is important for me because it allows having the tripod in my bag when travelling (checked bag). I delight traveling over the world (mainly Africa for safari but also USA, Iceland, .. on wish list Costa Rica, observation of Northern Lights, Canada for bears in Churchill.... and why not Antartica.

Can you share with me your recommendation based on your own experience or use of such products?

Thanks

Philippe